i cant seem to get him to open the cage whatever i do and i cant leave the conversation, how do i get him to leave the cage?

Go to the basemant, get a holotape, go back up, stand in front of the cage, open pipboy, go to "notes" section, find the first audio note, play it, done.

i have done that, i just dont know what dialogue patch to choose (i have the right science skill but not lockpick)

He should open the cage himself, just ask him about like what he's doing there and find out that he has a key on himself then ask him to use that key to get out.